Renovating a Historic Building
In 2016, the last modern masterpiece designed by world renowned architect Marcel Breuer, the Atlanta Fulton County Public Library was slated for demolition. One of the Fulton County commissioners described the original design as looking “more like a jail” than a welcoming space for learning and productivity. To save the iconic building from the wrecking ball, changes would have to be made. Originally, this brutalist concrete fortress for books was designed with an emphasis on keeping out daylight. The large floor plates were excellent for housing the original sorting equipment and storage for the library system of Fulton County. However, sorting was no longer centrally managed and the 200,000 SF facility was mostly empty and falling into disrepair. Librarians were housed in windowless rooms that were either too hot or too cold. The children's area in the basement was dark and forbidding. Multiple public surveys with thousands of users listed no daylight and oppressive interiors as the primary reason for not visiting the Central Library.
Renovating historic buildings is the best way to save embodied carbon as the steel structure and foundation components are already there. With this in mind the design team lead by Cooper Carry and Vines Architecture used analysis to show how minimal edits could save the library. Obviously, when editing an iconic piece of modernism, preserving the design intent of the original is paramount. The team won the $50M renovation project as part of a design competition. The board ultimately selected the winning team based upon their minimalist design aesthetic, historic preservation experience, and performance analysis capabilities.
Rapid technology advancements over the last decade changed the dictionary meaning of libraries from “a building or room containing collections books and media” to a "place of learning". Books and periodicals have shifted to laptops, Kindles, and VR Headsets. Research highlighted the importance of natural light in spaces involving learning. The users of the library made the same priorities clear in a survey conducted by the library system, which showed that 72 percent of the more than 3,200 participants were interested in seeing more windows added to the building.
01 Daylight Analysis
The Cooper Carry team had the difficult task of striking a balance of historic preservation along side modernization and enhanced learning. With access to daylight and quality views at the top of design proprieties, the team looked at Daylight Maps and View Quality Maps.
The analysis showcased above is the Spatial Daylight Autonomy (sDA) study which showcases the total percentage of the floor plate that gets sufficient daylight (300 Lux or above) for the operating hours of the building. The higher this number, the better. With the form of the building being fixed as the deep concrete box, the design team looked for opportunities to bring daylight in from atriums and by strategically opening up the facade. The daylight after the renovation is over7% more than original, but still lower as compared to new constructions. A well daylit building typically has an sDA of 55% or above (also as laid out in the LEED daylighting credit).
The diagram below shows a floor by floor comparison of the daylight from the original 1980s building to the 2020 renovation. They key public accessible floors like the first floor and second floor, showcase that the amount daylight has tripled.
In addition to daylight quantity, a few additional metrics including Radiation, Solar Gain and Glare are critical is assessing the quality of daylight and the potential of hot spots. The diagrams below show four different types of analysis, each answering a different questions. Starting from the top left corner:
Daylight Analysis: Studying the Spatial Daylight Autonomy (sDA). Key questions answered "Will occupants have access to daylight inside the library" and "what parts of the floor plate with have high daylight exposure, so that reading areas can be optimized around those". Measured as more 300 lux light more than 50% of the year during occupied hours of 8 am to 6 pm.
Solar Radiation Analysis: Studying the amount of direct sun energy falling in varying parts of the envelope. Key questions answered "Do specific parts of the facade have high direct radiation, creating hot spots?" and "Would the roof have sun access for solar panels?"
Sun Hours Analysis: Studying the number of hours of sun that certain parts of the building receive on average. Good for answering questions such as "how many hours of direct sun will be have on different parts of the facade" and " does the roof get enough hours of sun for varying landscape strategies for roof gardens?"
Glare Analysis: Annual Solar Exposure (ASE) metric. Key questions answered "Which areas of the floor plate are overly lit (above 1000 Lux for more than 250 hours a year), creating glare potential?" and "Where to strategically place shading devices on the facade?". For the Atlanta Central Library Project, the depth of the concrete block created enough of a "shading" effect that the team did not need any additional shading devices.
02 Views Analysis
Building occupants who can visually connect with outdoor environments while performing everyday tasks experience greater satisfaction, attentiveness, and productivity. Library patrons seated at computers, who often develop eye strain or dry eyes from looking at their screens for extended periods without a break, find relief in attractive distant views. The analysis above shows the "Quality Views" from inside the library and its use to evaluate the effectiveness of a building's design to provide building occupant substantial and beneficial views.
03 Energy and Carbon Analysis
After utilizing the daylight, glare, shadow, and radiation studies, the next step is to optimize the energy use for the library renovation project. Since upgrading the massing was not an option for this historic project, the team studied the impact of the envelope, HVAC, appliance, sensors, and adding photovoltaic panels to meet the high performance requirements. Starting out with an existing Energy Use Intensity (EUI) of 49.4 kBTU/sf/yr, the design team targeted an 30% EUI reduction of 35 kBTU/sf/yr. Starting with the auto-created model to meet base minimum requirements for the local regulations, they calculated an EUI of 44 kBTU/sf/yr. This meant that the team would need to upgrade varying aspects of the envelope and the systems to reach the energy efficiency targets. With high performance facades, sensors and upgraded systems, the team was able to achieve the EUI of 35 KBTU/sf/yr, allowing a 63% carbon reduction as compared to other buildings of this size and type. Hitting the carbon efficiency target was equivalent to avoiding 243 truck loads of ice melted per year or an entire iceberg. With building contributing to approx. 39% of all carbon emissions, this is a fairly significant reduction in the path of fighting climate change one building at a time.